Attenuation of noises disturbing tracked signals is typically performed in the prior art by using self-adaptive transverse filters which are effective as long as there is only a single noise source and the noise is carried by a plane wave. The noise components are estimated with the help of a transverse filter and are subtracted from the signal supplied by the disturbed sensor. The tracked signal, as corrected by subtraction, is continually put to use in the filter to adjust the various filter coefficients so as to obtain an optimum attenuation. In practice, the tracked signals received by a sensor, such as a microphone or a hydrophone, are usually drowned in noises comprising spectrum lines originating from different sources and the noises are picked up after having travelled along a variety of unidentified acoustic paths.
In these conditions, the results obtained are thus far inferior to those obtained when the above-mentioned conditions are observed.
Other relevant prior art, described in U.S. Pat. No. 4,232,381, provides for attenuation of spurious noises from the engine of a vehicle equipped with an acoustic signal receiver. The device comprises a rotation sensor which generates pulses for use by a synchronous filter which selects the fundamental and harmonic frequencies of the engine noise for the purpose of generating a correcting signal enabling static removal from the signal received by the acoustic signal receiver.
It is the object of the present invention to provide a method and two devices for attenuating wideband noises disturbing a tracked acoustic signal, which are both simpler and more efficient than the above-mentioned devices.